BREEDING OF STOCK.

New Zealand Herald, Volume LXVI, Issue 20273, 5 June 1929, Page 18

BREEDING OF STOCK.

MATING YOUNG ANIMALS.

MOST SUITABLE PERIODS.

THE EFFECTS OF DELAY.

Bl' n.B.T. Both the sheepman and dairy farmer nre frequently faced with the problem cf whether their young female stock is sufficiently developed at tho generally-ac-cepted age for maturing to be included in Iho breeding flock or herd. Tho majority of sheep farmers agree, I think, that it does not deleteriously affect two-tooth ewes to be put to the ram, provided they are normally well grown and developed. Thefee men contend that they get a much bettor return from two-tooth ewes, which nre bred from, than when they oro kept dry, even where tho lambing percentage is not big, and that, provided theso young ewes are dono well whilo they arc carrying the lamb, there is no check to normal growth and development.

Tliero are, however, quite a number of thoughtful, successful breeders who contend that it is a better practice to carry t the ewesl over four-tooth before putting them to the ram. They claim that under this system theio is no necessity to cull their sheep heavily as two-tooths, for, by keeping theis empty, a much larger number can be safely carried through tho winter. When culling is then undertaken of these maiden four-tooths it is found that fewer have to be rejected, for many late lambs that in the previous year would have been set aside on account of size or faulty development, have then been able to outgrow these defects. A Doubtful Advantage. I am inclined to doubt whether there is any pecuniary advantage to bo gained from breeding from two-tooth ewes in preference to carrying them through dry, for there are many expenses and risks incurred; in handling young breeding ewes, which, when totalled, appear to make the dry sheep the more profitable proposition. The position of tho ewe, however, must be considered. At first glanco it would appear obvious that it was better to carry the ewes through dry until four-tooth, thereby giving them every chance of developing full and producing more and better lambs at their first lambing. There are, however, other factors to be studied beside the rapid development of the ewe to maturity.

Under uncontrolled or natural conditions the ewe accepts service much earlier than under domesticated conditions. There oppears to be no set time or age, the first " heat" period being dependent on the animal's 1 development. Prior to sufficient physical development having been attained the female cannot conceive, even though mated, during a " heat" period, because of the presence of acidity, which destroys the spermatozoa' from the malo. Nature, therefore apparently takes care that conception will not occur at, an age when it will threaten the dam's survival or development. Results of Delayed Breeding. When the time of this first mating is delayed for another year, the organs of the ewe ceaso to develop, the pilkie bones become harder, and less elastic, and the milk-secreting organs commence to atrophy from lack of use. The ewe also puts on an amount ol surplus condition, which would ordinarily go to the nourishment of the foetus, and this internal fat tends to restrict the space available to the uterus.

It is, therefore, usually the case that, although four-tooth maiden ewes are bigger and better conditioned than, ewes of the same age which have been mated, they will produce only a small percentage of weedy lambs. A great many ewes which have been kept as maidens until they are four-tooth will also be found to be permanently barren. Provided in-lamb, two-tooth ewes have plenty of winter keep, tliero is no reason why they should suffer in growth or development when compared with dry ewes ofj the same ago. Condition and wool growth will'certainly not bo so good, but these are not nearly so important ultimately as a propensity to breed regularly. It is apparent from the lambing percentages which we normally get from our two-tooth ewes that while some of them are put to the ram too early, the majority are mated too late. It is most important, in view of their breeding ability, in later life to secure as many lambs as possible from these young sheep, and it would therefore be well worth trying a longer season with the rams. A Longer Mating Season. Without incurring any considerable riskit should be a profitable practice in the North Island to put the rams with the two-tooths about the middle to the third week in February, leaving them in—if the rams were sure to be still active — for a fortnight after they were taken out of the older owes. This would certainly mean a'protracted two-tooth lambing, but (he extra trouble incurred would bo more than repaid in the future breeding performance of the ewes.

What is noticed in the ewe in respect of leisured ability to produce milk, owing to the arrest in development or atropb.v of the milk-secreting glands, when breeding is delayed beyond the normal time, is still more noticeable in dairy cattle. If h duiry farmer wishes his heifers to produce their maxmum throughout their lives, he should never delay putting them with the bull at the normal time, on account 01 their being a little backward in size. ,i

With both cattle and sheep it is always possible to remedy mider-size by liberal feeding, even during (he period of gestation, but no after-treatment will correct the evils of delayed breeding.